1. Field of the Invention
The present invention relates to a microstrip line-waveguide conversion structure, to an integrated circuit package for high frequency signals employing this conversion structure, and to a manufacturing method therefor, and in particular, relates to a microstrip line-waveguide conversion structure, an integrated circuit package for high frequency signals provided with this conversion structure and a manufacturing method therefor, which are adopted for the airtight sealing of integrated circuits employed in the millimeter band.
2. Background Art
In general, in semiconductor integrated circuit modules employing the millimeter or micrometer wavebands, it is necessary to provide a structure having an airtight seal in order to increase reliability. However, in the millimeter waveband, the physical dimensions of the interface in coaxial bonds employing the glass sealing which was employed in the micrometer waveband become small, and the requirements for manufacturing precision become severe, so that this has not been conducted.
Techniques in which semiconductor integrated circuits are sealed in an airtight manner using waveguides have been proposed. For example, in xe2x80x9c60 GHz Band Signal Receiving Modulexe2x80x9d, which is found on page 136 of the first volume of the Collected Papers of the Electronics Society Conference of the Electronic Information Communication Study Group of 1995, a structure is disclosed which directly converts high frequency signals from a microstrip line to a waveguide and outputs these to the exterior. FIG. 15A is a plan cross-sectional view showing the structure of the high frequency interface portion of a conventional integrated circuit package (hereinbelow referred to as Conventional Example 1), while FIG. 15B is a cross-sectional view taken along the line Ixe2x80x94I in FIG. 15A.
As shown in FIGS. 15A and B, the integrated circuit package of Conventional Example 1 is provided with a package base portion 40 which is made from metal or the like, a waveguide 41 which extends approximately vertically within the package base portion 40, a dielectric substrate 42, which is provided on package base portion 40 and which is disposed so that the end portion thereof is positioned within waveguide 41, and a cover portion 43, which is made from metal or the like and which closes the upper portion of package base portion 42. A microstrip line 44 which serves to transmit the high frequency signal is provided on top of the dielectric substrate 42.
A microstrip line-waveguide converter 45, which is connected with the microstrip line 44, and which serves to conduct conversion between the transmission mode of the microstrip line 44 and the transmission mode of the waveguide, is provided on top of the end portion of dielectric substrate 42.
A sealing dielectric substrate 46 is applied to the lower portion of waveguide 41, and by means of this, airtight sealing of the package is realized.
Furthermore, FIG. 16 is a cross-sectional view showing the package for MIC which is disclosed in Japanese Patent Application, First Publication No. Sho 58-215802 (hereinbelow referred to as Conventional Example 2).
As shown in FIG. 16, the conventional MIC package is provided with package main body 50 comprising a metal such as copper or the like, a concave portion 51 which is formed in the central portion of this package main body 50 and which provides a carrier, waveguides 52 which are formed at both end portions of the main body 50 and which communicate with concave portion 51, a cover 53, which is attached by welding or the like to the upper portion of the package main body 50, a microstrip line 54 for the terminal for high frequency input and output, an end of which projects within the waveguides 52, and an airtight sealing plate 55 comprising an insulator material such as silica glass or the like, which is attached to the bottom portion of waveguides 52.
Furthermore, when a portion or the entirety of waveguides 52 is filled with a dielectric material and sealed in an airtight manner, it is possible to make the waveguides 52 small, so that it is possible to achieve a reduction in size of the package.
The following problems were present in the conventional technology described above.
(1) In the integrated circuit package of Conventional Example 1, interface mismatching is produced at the portion of dielectric substrate 46 which is affixed to waveguide 41, and the reflection coefficient becomes high, so that there is a large passage loss. FIG. 17 is a graph showing a simulation of the passage loss when a conventional integrated circuit is employed. It can be seen from FIG. 17 that the passage loss increases as the frequency increases in conventional integrated circuit packages. Accordingly, it is difficult to employ the integrated circuit package of Conventional Example 1 at millimeter band frequencies of 60 GHz or more.
In the MIC package of Conventional Example 2, as well, as in the package of Conventional Example 1, the interface characteristics are poor at airtight sealing plate 55, and the passage loss increases. In order to prevent passage loss, attempts have been made to construct the airtight sealing plate 55 from a thin material having a low dielectric constant; however, the airtight sealing plate 55 is easily broken, so that there is a problem with the durability thereof.
(2) Dielectric substrate 46 or airtight sealing plate 55 are attached to the bottom portions of waveguides 41 and 52 in order to create an airtight seal, so that the effects caused by the adhesive employed for the affixing or the accuracy of attachment can be striking, and it is difficult to achieve optimal characteristics.
(3) The conversion of the transmission mode is conducted by the microstrip lines 44 and 54 which project in the form of antennae into waveguides 41 and 52, so that it is not possible to employ broadband frequencies. For this reason, the uses are restricted.
The present invention is carried out to solve the problems described above; and it is as an object thereof to provide a microstrip line-waveguide conversion structure, and an integrated circuit package for high frequency signals employing such a conversion structure, and a manufacturing method therefor, which are capable of reducing the passage loss even when millimeter band frequencies are employed, in which the structure is simple, and which may be applied to broadband frequencies.
The microstrip line-waveguide conversion structure of the present invention has a dielectric substrate, and a microstrip line which is provided on the dielectric substrate and is provided with widened portions which are formed so as to broaden a conductor, wherein is provided a waveguide portion containing the widened portions on the dielectric substrate.
It is preferable that transmission mode converters formed so as to incline in the direction of the widened portions be provided in the vicinity of the widened portions of the microstrip line.
The high frequency signal transmitted is a signal in, for example, the millimeter waveband.
In the first integrated circuit package for high frequency signals of the present invention, an integrated circuit for high frequency signals which is provided on a base member, and a microstrip line which is provided with widened portions formed so as to widen a conductor, are covered from the upper portion thereof in an attached manner by a metal cover, and, at the point of contact between the metal cover and the widened portions provided in the microstrip line, a waveguide portion formed on a dielectric substrate is provided, and an airtight seal is formed.
It is preferable that transmission mode converters formed so as to incline in the direction of the widened portions be provided in the vicinity of the widened portions of the microstrip line.
The shape of the waveguide portion is determined by the width and thickness of the dielectric substrate.
The second integrated circuit package for high frequency signals of the present invention is provided with: a base member on which an integrated circuit for high frequency signals is installed, a dielectric substrate which is provided on the base member, a microstrip line which is provided on the dielectric dielectric substrate, is electrically connected with the integrated circuit for high frequency signals, and which is provided with widened portions formed so as to widen a conductor so as to be approximately equivalent to the width of the dielectric substrate, a frame member in which a concave portion, which engages with the widened portions of the microstrip line and the dielectric substrate, is formed, and in which an opening which encloses the periphery of the integrated circuit for high frequency signals is formed, and a cover member, which seals the opening of the frame member, and seals in an airtight manner the integrated circuit for high frequency signals; wherein a waveguide portion, which is formed on the dielectric substrate at a point of contact between the widened portions provided in the microstrip line and the concave portion of the frame member, is provided, and an airtight seal is achieved.
The third integrated circuit package for high frequency signals of the present invention is provided with: a base member on which an integrated circuit for high frequency signals is installed, a dielectric substrate which is provided on the base member and which engages with a concave portion, a microstrip line which is provided on the dielectric substrate, is electrically connected with the integrated circuit for high frequency signals, and which is provided with widened portions formed so as to widen a conductor so as to be approximately equivalent to the width of the dielectric substrate, a frame member which is positioned on the widened portions of the microstrip line, and in which an opening which encloses the periphery of the integrated circuit for high frequency signals is formed, and a cover member, which seals the opening of the frame member, and seals in an airtight manner the integrated circuit for high frequency signals; wherein a waveguide portion, which is formed on the dielectric substrate at a point of contact between the widened portions provided in the microstrip line and the frame member, is provided, and an airtight seal is achieved.
The microstrip line may be formed so as to extend to the outside of the frame member, and portions of the microstrip line extending outside the frame member may serve as input and output interface portions for high frequency signals.
The frame member may be provided with a first frame portion and a second frame portion which are disposed with a predetermined space therebetween, and a pair of third frame portions provided at both end portions of the first frame portion and the second frame portion, and the opening may be formed within the first frame portion, the second frame portion, and the third frame portions.
The fourth integrated circuit package for high frequency signals of the present invention is provided with: a base member on which an integrated circuit for high frequency signals is installed, a dielectric substrate which is provided on the base member, a microstrip line which is provided on the dielectric substrate, is electrically connected with the integrated circuit for high frequency signals, and which is provided with widened portions formed so as to widen a conductor so as to be approximately equivalent to the width of the dielectric substrate, a frame member in which a concave portion, which engages with the widened portions of the microstrip line and the dielectric substrate, is formed, in which an opening which encloses the periphery of the integrated circuit for high frequency signals is formed, and in end portions of which notched portions are formed, and a cover member, which seals the opening and the notched portions of the frame member, and seals in an airtight manner the integrated circuit for high frequency signals; wherein
a waveguide portion, which is formed on the dielectric substrate at a point of contact between the widened portions provided in the microstrip line and the concave portion of the frame member, is provided, and an airtight seal is achieved, and a spacing portion formed by the notched portions of the frame member, the base member, and the cover member serves as the input and output interface portion for high frequency signals converted to the transmission mode of a waveguide employing air as a medium.
It is preferable that the frame member be provided with a first frame portion and a second frame portion which are disposed with a predetermined space therebetween, and third frame portions which are provided at a position within end portions of the first frame portion and second frame portion and which come into contact with the widened portions of the microstrip line, and that a concave portion, which engages with the widened portions of the microstrip line and the dielectric substrate, be formed in the third frame portions, and the third frame portions be provided with an inclined surface which is outwardly inclined to the side of the cover member, from the contact surface at which contact is made with the upper portion of the widened portions of the microstrip line.
The fifth integrated circuit package for high frequency signals of the present invention is provided with: a base member on which an integrated circuit for high frequency signals is installed, a dielectric substrate which is provided on the base member, a microstrip line which is provided on the dielectric substrate, is electrically connected with the integrated circuit for high frequency signals, and which is provided with widened portions formed so as to widen a conductor so as to be approximately equivalent to the width of the dielectric substrate, a frame member, in which a first opening, which encloses the periphery of the integrated circuit for high frequency signals, and a second opening, which is formed outside the first opening and with a predetermined space therebetween, are formed, and in which a concave portion, which engages with the widened portions of the microstrip line and the dielectric substrate, is formed between the first and second openings, and a cover member, which seals the first and second openings of the frame member, and which seals in an airtight manner the integrated circuit for high frequency signals; wherein
a third opening, which communicates with the dielectric substrate at the side of the second opening, is formed in the base member, a waveguide portion, formed on the dielectric substrate at a point of contact between the widened portions provided in the microstrip line and the concave portion of the frame member, is provided, and an airtight seal is formed, and the third opening serves as the input and output interface portion for high frequency signals converted to the transmission mode of the waveguide employing air as the medium thereof.
It is preferable that the third opening of the base member be formed so as to extend approximately vertically downward and be formed so as to widen in the downward direction.
It is preferable that the dielectric substrate be formed from a material having the characteristics of being non-moisture absorbent and having low dielectric loss, such as, for example, alumina.
It is preferable that the frame member and the cover member be formed from a metal such as, for example, Kovar, copper tungsten, or copper.
It is preferable that the base member be formed from a metal such as, for example, Kovar, copper tungsten, or copper.
It is preferable that the base member be formed from, for example, a ceramic multilayered substrate, and that electrical wires connected electrically with the integrated circuit for high frequency signals be disposed between layers of the multilayered substrate.
It is preferable that a transmission mode converter formed so as to be inclined in the direction of the widened portion on the side of the frame member be provided in the microstrip line.
The base member and the frame member may be formed integrally.
The high frequency signals transmitted may be, for example, millimeter waveband signals.
In the manufacturing method for integrated circuit packages for high frequency signals of the present invention, an integrated circuit for high frequency signals, and a microstrip line provided with widened portions formed so as to widen a conductor, are provided on a base member, and
next, the integrated circuit for high frequency signals and the widened portions of the microstrip line are attached from above using a metal cover, and a waveguide portion, which is formed on a dielectric substrate at a point of contact between the widened portions provided in the microstrip line and the metal cover, is provided, and an airtight seal is achieved.
Furthermore, in the manufacturing method for integrated circuit packages for high frequency signals, the following are provided:
(1) a process for preparing a base member having an integrated circuit for high frequency signals, a dielectric substrate, and a microstrip line, which is provided on the dielectric substrate, is electrically connected with the integrated circuit for high frequency signals, and wherein is provided widened portions formed so as to widen a conductor so that the width thereof is approximately equal to that of the dielectric substrate,
(2) a process for disposing a frame member provided with frame portions in which openings are formed and in which a concave portion is formed so that the concave portion of the frame portions engages with the widened portions of the microstrip line and the dielectric substrate, and the openings enclose the periphery of the integrated circuit for high frequency signals, and for attaching the frame member to the base member, and
(3) a process for attaching a cover member to the upper portion of the frame member, closing the opening in the frame member, and sealing the integrated circuit for high frequency signals in an airtight manner; wherein a waveguide portion, formed on the dielectric substrate at a point of contact between the widened portions provided in the microstrip line and the concave portion of the frame member, is provided, and an airtight seal is achieved.
The frame member is attached to the base member by soldering or by welding, and the cover member is attached to the frame member by soldering or by welding.
The high frequency signals transmitted are, for example, signals in the millimeter waveband.
In accordance with the microstrip line-waveguide conversion structure of the present invention, by means of providing a waveguide portion containing a widened portion on a dielectric substrate, it is possible to convert the transmission mode of high frequency signals to the transmission mode of a dielectric waveguide.
In accordance with the integrated circuit package for high frequency signals of the present invention, by means of the waveguide portion formed by the metal cap attached on top of the base portion, it is possible to simultaneously realize the conversion of high frequency signals to the transmission mode of the dielectric waveguide and the airtight sealing of the integrated circuit for high frequency signals.
In accordance with the manufacturing method for integrated circuit packages for high frequency signals of the present invention, it is possible to obtain an integrated circuit package for high frequency signals which is provided with the microstrip line-waveguide conversion structure described above by means of an extremely simple process.